Mix egg and cream cheese spread in large bowl until blended. Add rice, 1/2 cup bread crumbs and 1/4 cup Parmesan; mix well.
Use moistened hands to roll rice mixture into 16 balls, using about 2 Tbsp. rice mixture for each ball.
Cut each stick of string cheese into 8 pieces; insert 1 mozzarella piece into center of each ball, completely enclosing mozzarella with rice mixture.
Combine remaining bread crumbs with 1/4 cup of the remaining Parmesan in shallow dish. Roll rice balls, 1 at a time, in bread crumb mixture, turning to evenly coat all sides of each ball.
Heat oil in Dutch oven on medium-high heat to 325°F. Working in batches, add rice balls to hot oil; cook 4 to 6 min. or until evenly browned, turning occasionally. Use slotted spoon to remove rice balls from oil; drain on paper towels. Transfer rice balls to plate; sprinkle with marjoram and remaining Parmesan.
Heat pasta sauce. Serve with the rice balls.