blood worms, black worms, or tubifex worms are the most common worms. live isnt recamended unless you culture your own worms cause of parasites. freeze dried and frozen worms are safer. live worms hold more nutrients, tho. if the jewels turn out to get really big, you could feed them earth worms and the like, if they arent too big.
you could also use cichlid pellets or cichlid sticks that are appropirate sizes. flakes arent efficent means of food. they are just too small for medium sized to larger cichlids.
I think tiger barbs are alright, as long as the jewels are small and both types of fish grow up together, so that the barbs continue to be a -safe size- "larger" than the jewels. as in the jewels wont reck on the fish cause they are too big to consider larger peieces of food.
I would get a group of 5 going so the aggression is spread and the jewels see them as a group in the environment rather than a few fish to be killed.
I have blue acaras which arent that agressive now in with some 2 inch black skirts and the skirts arent harrassed as much as they would be. there are nine black skirts rather tahn 2.
if you want, you could get rid of the barbs and get something else that could live with them. Im not sure what other fish could live with jewels.