Hart has been criticised for some of his performances for Manchester City this season and was held culpable for England's 4-2 defeat to Sweden in November.
But Gerrard said: "We're very lucky to have Joe Hart. The goalkeeper position has always been up for debate over the last four or five years and questions were always being asked over who is the No1. Joe has come from nowhere to grab it with both hands and has been fantastic for the country ever since.
"Every player has slight dips in form, I've had plenty, but it's how you react and bounce back. He has certainly been in good form of late.
"He is a world-class keeper and if England are to achieve any success in the future, he will play a major part.
"Brazil's keeper, Julio Cesar, is in great form but we wouldn't swap Joe for anyone in the world."