Cut peppers lengthwise in half. Remove and discard membranes and seeds.
Mix meat, rice, peas, and 1/4 cup each water and barbecue sauce just until blended; spoon into peppers.
Combine remaining water and barbecue sauce in slow cooker sprayed with cooking spray. Add peppers, filled sides up; top with VELVEETA. Cover with lid. Cook on LOW 5 to 7 hours (or on HIGH 2-1/2 to 3-1/2 hours).
Serve peppers topped with barbecue sauce from slow cooker.