The Manchester United striker is the only player to have scored so far for the Under-21s in Denmark and will lead the line against the Czech Republic tonight.
But two years ago he was taken off shortly after coming off the bench in a 1-1 qualifying draw with Greece.
Back onside: Danny Welbeck has become one of England Under-21's key players
Pearce said: 'I put him on but, after 20 minutes, he wasn't running around so I substituted him.
'When you do that to any player it hurts. I told him that when you enter the pitch for England you have to work harder than he had for those 20 minutes.
'Credit to him, he took the lesson from that. He's rolled his sleeves up and his work-rate is sensational.
'A lot of the upturn in the Under-21s over the past 15 months or so has been down to him.' Staying put! Pearce lands new England U21s deal and now targets Czech scalp Spain U21 1 England U21 1: Welbeck levels late after low blow from SpaniardAll the latest Manchester United news, features and opinionAll the latest Sunderland news, features and opinion
Explore more:People: Stuart Pearce, Danny Welbeck Places: United Kingdom, Greece, Czech Republic, Denmark