The eight, who bring both Regional and international experience to the squad, include Cory Hill and fellow Blues forward Luke Hamilton and wing wizard Harry Robinson who was a member of Warren Gatland's Six Nations training squad and the Wales Sevens squad this season.
They are joined by Dragons centre Jack Dixon and Ospreys Matthew Morgan, Tom Habberfield, who has been part of the Wales Sevens squad this season, Eli Walker and four-times Wales capped Tom Prydie who is currently on loan to London Wasps.
Of the eight, only Dixon and Robinson played any part in the 2012 Under 20 Six Nations, with one game each, Dixon against Italy and Robinson against England at the Stoop. Loosehead prop Gareth Thomas is the only other addition to the squad since the Six Nations.
Ten of the 28 players - backs Ross Jones, Eli Walker, Iolo Evans, Matthew Morgan and Jonathan Evans and forwards Kirby Myhill, Jamie Sollis, WillGriff John, Luke Hamilton and Cory Hill - were part of the squad that competed in last season's Junior World Championship in northern Italy. Blues lock Hill has been named squad captain for the tournament with Six Nations captain Kirby Myhill selected as vice-captain.
Wilson said: "The players who have joined the squad since the Six Nations have already brought a new intensity to our training sessions and we hope that their Regional and international experience will help lift our playing performances too.
"The additional players have certainly improved our strength in depth, but now we must have a good month training in order to get on the plane feeling well prepared."
Wales play Fiji, New Zealand and Samoa in the Pool stage of the IRB tournament, a group that will certainly test the Welsh youngsters.
"It is an extremely physical group," added Wilson, "and we must meet that challenge head on if we want any chance of progressing to the top half of the draw.
"New Zealand have proved year after year that they are the strongest side in the world at this age, so they will again be a huge challenge, but we must target our other Pool games against Fiji and Samoa. We saw last season that those sides are very dangerous and we must execute the right game plan against them. We must be physically and mentally ready for all three games."
Wales play Japan in a friendly on Tuesday 15 May at St Helens before heading to South Africa on May 30.
Wales Junior World Championship squad
Rob Evans (Scarlets), Gareth Thomas (Scarlets), Kirby Myhill (Scarlets), Jamie Sollis (Dragons), Darran Harris (Blues), WillGriff John (Blues), Samson Lee (Scarlets), Cory Hill (capt, Blues), Matthew Screech (Blues), Rhodri Hughes (Ospreys), Ieuan Jones (Dragons), Ellis Jenkins (Blues), Daniel Thomas (Scarlets), Luke Hamilton (Blues), Dan Baker (Ospreys)
Jonathan Evans (Dragons), Tom Habberfield (Ospreys), Sam Davies (Ospreys), Matthew Morgan (Ospreys), Owen Williams (Scarlets), Jack Dixon (Dragons), Thomas Pascoe (Blues), Iolo Evans (Scarlets), Luke Morgan (Ospreys), Harry Robinson (Blues), Eli Walker (Ospreys), Tom Prydie (London Wasps), Ross Jones (Ospreys)