There are a few possibilities.
When a pump fails it contaminates the system with meatl and rubber. It should be flush and filled in order to assure that there are no problems. Problems that occur can be; Pr-Mature wear of pump
Blocked passages created a harder steering feel
Problems with, "Speed Senstive Steering"
Damage to rack and pintion seals
The fron end suspension and overall alignment of the car can affect it as well.
If ball joints are not servicable, (cannot be greased and are sealed), they can tighten steering when they begin to fail. They are especially prone to the loxer ball joint.
Tension bar and other bushings can deteriorate and cause steering drag.
Upper mount for the struts can do the same thins.
So, there are a lot of variable. Take it to a dependable front end shop and have the suspension looked at as it is something that is overlooked as a safety issue.