bloodworms are great, otherwise worms, finely diced meat (ox heart, fish, prawns, shrimp etc) small aquarium/pond snails, you can also get hot house turtle food (meaty fish stuff) from wetpets and other pet shops i presume, turtle pellets (nutrafin is a good one) or trout pellets, duckweed for abit of greens or cucumber/zuchini, oxygen weed etc (should offer greens often as sooner or later they'l get a taste for em & as they get older more an more greens should be part of their diet.
IMO variety is the key (like with most living things) so try mix it up abit form time to time!
Not everyone would agree but when they get older little pinkies which are a delicacy for turtles baby mise / rats
Other important thing is calcium, you can get calcium blocks from pet shops/ trademe or calcium tablets for dogs or cheaper still cuttle bones for birds which you will find in the supermarket.
Also if you really wana go all the way you can get calcium and mineral powder for reptiles (think someone on tm is selling it at the mo) and dust there food in tht once a week or so.
hope your turtles have settled in well :lol: