Wigan winger McManaman has been rewarded for his fine recent form with his first call-up to the Under 21s for the finals in Israel next month.
McManaman, who has represented England at Under 20 level, has caught the eye in recent weeks and was named man of the match in last weekend's FA Cup final.
Pearce has worked with McManaman before at the Under 20s World Cup in Colombia and he feels he will be a valuable addition to the squad.
"He [McManaman] has done really well," Pearce told Sky Sports News. "I have seen a fair bit of him over the last six weeks, myself and my scouts have picked up every game he has played over that period of time.
"I have been fortunate enough to have worked with him with the Under 20s two years ago in Colombia in a tournament there so I know what he is like as a boy as well which gave me a real good insight into him.
"But at this moment in time he is doing fantastically well for Wigan and I think he thoroughly deserves his place in the squad."
Pearce also backed Roberto Martinez for the job he has done in bringing through McManaman.
"I think Roberto has done a fantastic job with him," added Pearce.
"He's kept him undercover and at the right time fed him into the first team, and he seems to be thriving and seems to be improving game by game.
"We are pleased to have him in the squad and I think him having the experience of the Under 20 tournament in Colombia will stand him in good stead.
"I don't think he will come into the squad nervous in any shape or form. I think it will be a great tournament for him."