The mates in SolidWorks keep the solid bodies in the correct location in space.

When the geometry comes into ANSYS for the first time, you have to either manually or automatically define Contacts.

If you have the SolidWorks CAD interface, so ANSYS brings the model straight into Mechanical from SW, then you can bring geometry updates from SW into Mechanical and all the work you have previously done creating contacts should be maintained and all the contacts will simply update to the new geometry.