Preheat oven to 350°F. Spray shallow 2-quart casserole with cooking spray; set aside. Combine mayonnaise, relish, mustard and pepper in large bowl; mix well. Add rice, sauerkraut, corned beef and 1/2 cup cheese; mix lightly to coat. Spoon into prepared casserole. Top with tomatoes; sprinkle with remaining 1/2 cup cheese and bread crumbs. Bake until hot and bubbly, about 30 minutes.