Place clams and 5 cups water in a large pot. Bring to a boil.
Add shrimp and cook, covered, for 5 minutes. Turn off heat and let seafood sit in liquid. Heat the olive oil in a large Dutch oven. Add chicken, rice, pepper, onion and garlic and stir-fry for 5 minutes.
Add 3 1/2 cups cooking liquid from the seafood plus salt and pepper to taste. Cover and simmer for 25 minutes until rice is fully cooked. Stir in the diced tomatoes and Alfredo sauce. Stir in the seafood. Heat covered for 10 minutes. Serve and enjoy!