Can a water pump gone bad break a brand new radiator installed by a mechanic in just 4 months?

4 months ago, my car over heated and I took my car to a shop. They replaced the radiator, resevoir tank, and all the hoses coming and going. They told me my water pump might be going bad soon and they can replace it for $600 after I took out a high interest loan of $900 to pay them! I said not now. Two days ago, my car over heated again. There was a giant leak on the side of the radiator and the car would crank but not turn over and it sounded exactly like the first time it overheated. They said the water pump caused the massive leak while a few friends of mine in which one is a mechanic for domestic cars say that wouldn't be the cause.