Peas are good once in a while, but should never be included as part of a regular diet. Likewise, bloodworms are very nutritious, but you probably wouldn't be in very good shape if you ate spinach for the rest of your life, would you?
All of my bettas have been stubborn with pellets, but with enough patience they will eat them. Heck, a betta will even bring itsself to eat peace-lily roots if you stuff 'em in one of those dreadful vases! Cut him off from bloodworms and be persistent until he eats them. No animal will let itsself starve so he will eventually break down and eat them.
Fish will eat and spit out their food multiple times to 'break it up' if it seems to big, but your betta will eventually learn to crunch them. Also, the gel they are encased with to make them float can fool a betta into thinking that the pellet is not actually food. Once he gets past the gel, he may discover that they aren't bad!
Good luck and remember: NEVER RELENT!