Cut off tops of peppers; remove seeds and membrane. Precook the pepper cups in boiling salted water about 5 minutes; drain. (For crisp peppers, omit precooking.) Sprinkle inside of cups with salt.
Cook the beef and onion till meat is lightly browned. Season with salt and pepper. Add tomatoes and water. Add rice and Worcestershire sauce. Cover and simmer till rice is tender, about 15 minutes. Stir in cheese.
Stuff peppers; stand upright in 10x6x1 1/2-inch baking dish. Bake uncovered at 350°F for 20 to 25 minutes.