Where can the OP find or buy Bearings at? also if the OP dose this and finds an issue he will void his warranty! just saying, I totally endorse what you wrote but as long as the OP know what he or she is getting in to.
Thats a very valid point regarding warranty. Sorry, I forget sometimes since I have been building, maintaining and repairing my own aircraft for years.
Yes, if you do open anything up then obviously the DJI warranty will be void so you do anything like this at your own risk. If you are not comfortable working on your own machine then it is always best to send it in.
With regards to the bearings in the motors they are nothing special and are standard sized 6852Z Metal Shielded bearings available pretty much anywhere on the planet! They can also be known as 685ZZ or 6852ZR
Standard dia: 5/11/5 (Bore 5mm, OD 11mm Width 5mm). In fact, if you replace them with ceramic versions they will be of higher spec than the ones DJI fit at manufacture!
Please note, as I have explained before on this forum, I do not work or have any affiliation with either DJI or any of its subsidiaries nor do I receive any payment, incentive or otherwise for recommending anything DJI.
Any advice I give is gathered from my nearly 30 years RC experience of designing, building, flying, crashing and repairing anything radio controlled.
Hope that clarifies things........ And do be careful if you decide to go the route of opening up the Inspire yourself.