Cavitation problems on the 6.4 show up primarily in the front cover of the engine / back of the coolant pump. Cavitation causes pinholes to develop here and allow coolant and oil to mix.
Regular coolant nitrite testing and VC-8 addition as needed is critical. The specified test intervals have been reduced and the testing is now specified for all maintenance schedules, not just the severe duty schedule. Given the low cost of the test strips and the ease of testing (sampling from the degas bottle is ok), I'd recommend testing at every fuel filter change (~10k intervals).
The front cover has also had a design change that seems intended to reduce cavitation issues. One of the techs posted pictures of a cavitated old style cover and the new style cover that it was replaced with. The new style cover had an extra tab of material added in the coolant flow path near where the cavitation damage showed on the old style cover. This tab would seem to be intended to modify the coolant flow and eliminate a low pressure area where cavitation is most likely to occur.
Cavitation has nothing to do with filtering of the coolant, so a filter would not have any effect on the cavitation issue.