Chances are they are Fruit Fly....And believe me NOTHING gets rid if them.
You Can always try those fruit fly home made traps but they dont work for me . Or then again they could be moth larvae

Google -- control Fruit Fly - This may give you some help or tips

Make sure you are not leaving the toms on the vine too long.

Well I'm confused - fruit fly breeds in soil, not in fruits, well, in the UK anyway, and Tomato Moth Caterpillar, link here

http://www.marshalls-seeds.co.uk/blog/article/tomato-moth-caterpillar-bgid120.html

only gets inside a fruit by chomping its way in from the outside, and that means obvious holes.

But its possible they're housefly larvae, if you left the fruits on too long, and they were going soft and were therefore accessible.