Water pump hose connectors

Pipe wrenches often crush the sides in, which appears to have happened to one pipe. Yours look quite rust-free, so shouldn't be impossible. Let penetrant soak for a day. Work back & forth to help flush the rust out. Rapping on the end of the pipe also helps hydro-shock the rust out once penetrant has seeped in. Many people swear by heat, but might need to get it almost red hot to help.