The Hammers are short of attacking options, with key striker Andy Carroll out with a troublesome knee injury.
"He's certainly the type of player West Ham could do with at the moment, a player that is going to get goals," said Ashton, according to The Mirror.
"I think the West Ham fans wouldn't mind having Jermain back even though he divided the club when he left.
"I'm like a lot of players who have played with Jermain Defoe who will definitely say he's up there with the best finishers we've ever played with."
West Ham currently find themselves 15th in the Premier League table.