Wenger feels Campbell's presence, both on and off the pitch, has proved useful and he is in talks with the defender over a possible new contract.
"I believe it is fantastic to see how well Sol has come back. When he has his mind on the game he is unbelievable," said Wenger.
"Sol is a strange guy because when he is focused sometimes he can be very detached - but when he is in with you, he is 100 per cent, not 99, that is what I like.
"In the dressing room as well he has been very good.
"If Sol sets himself a target he is an unbelievable soldier."
Wenger believes Campbell, a former England skipper, still has something to offer the national team and would not let anyone down in South Africa.
"I just see that many centre-backs are injured, so why not?" said the Frenchman.
"Sol has got the experience and it is up to Capello to decide."
Wenger continued: "Of course others have an advantage because they are younger, but if England have a problem in numbers Sol is always there.
"I do not select the team and I do not say Capello has to take him - I just say you compare him today in the Premier League with the other centre-backs and he does not suffer in the comparison."