[sbaert]

Bearings do not come loose by themselves. I suspect it is the wrong bearing as evidenced by the non factory grease.

Do NOT drive the car until this issue is investigated and fixed.

OR you could wait until you see one of your wheels going faster than you are and see what happens.

 

[sbaert]

Replacement with a new hub assembly is the only solution.

 

[sbaert]

The answer is in post #12

 

[sbaert]

Based on the pic, it looks like the bearings were already replaced before.

 

[sbaert]

... unless the entire part is bad is some fashion.

Hence why I recommend (for the 3rd time) to put in a entire hub assembly. No need to reinvent the wheel (pun intended).