In a large saucepan, bring the water, potatoes, carrots, celery, onion, salt and pepper to a boil. Reduce heat; cover and simmer for 8-10 minutes or until vegetables are just tender. Remove from the heat; do not drain. , Meanwhile, in another saucepan, melt the butter. Stir in flour until smooth; gradually add milk. Bring to a boil; cook and stir for 2 minutes or until thickened. , Add cheese and stir until melted. Stir into the undrained vegetables; return large saucepan to the heat. Add corn and ham; heat through, stirring occasionally.