Beat eggs with water; season with salt and pepper. Set aside. Spray an 8-inch omelet pan or nonstick skillet with cooking spray. Heat skillet over medium heat.
In small saucepan, heat pizza sauce.
Add sausage to skillet. Cook until browned. Set aside.
Add pepper, onion, mushrooms, and seasoning to skillet. Cook, covered, over medium heat until peppers are soft, about 2 to 3 minutes.
Add cooked sausage to pepper mixture. Pour eggs over pepper mixture. (Eggs should set immediately at edges). With an inverted pancake turner, carefully push cooked portions at edges toward center so uncooked portions can reach hot pan surface, tilting pan and moving cooked portions as necessary. Reserving some sauce for topping, when top of omelet is thickened and no visible liquid egg remains, spoon hot sauce over half of the omelet. Top with pepperoni and mozzarella cheese. Slide from pan onto plate. Spoon on remaining sauce. Sprinkle with Parmesan.