Cut Roast in half. Place the roast, peppers and onion mix, mushrooms, marinara sauce, beef stock, Italian Seasoning, diced tomatoes, and Worcestershire sauce in the instant pot. Close the lid, make sure the nozzle is on seal, hit the meat and stew button, up the time to 60 minutes and allow to cook.
Meanwhile slicing the rolls in half, sprinkle mozzarella and parmesan cheese on both sides of the roll, and toast in the oven on broil until cheese is melted.
Once Instant Pot goes off allow to depressurize, remove the lid, remove the beef, leave peppers onions and mushrooms in instant pot, turn instant post on saute and allow the juices to reduce.
While sauce is reducing shred the beef and place back into the sauce. Turn Instant Pot off.
Liberally scoop the beef, onions, and pepper mixture onto the rolls with the melty cheese and serve.
You can substitute pork loin or 6 chicken breasts for the beef roast if you are not a beef eater.