"work in progress" is a common set phrase referring to an activity or task that is as yet unfinished. "work in process" is a specialist or technical phrase meaning partly finished goods in a company's production system. As far as I know, it is not used in general everyday English, and would look like an error for the above if used outside its usual context.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.