Vlad,
I don?t claim to be a taper-roller bearing expert, but I do have experience with the design and maintenance of landing gear wheels used on wide-body aircraft (brand A and brand B). The photos depict classic spalling (fatigue and subsequent loss of the metal). Trouble shooting bearings is frequently tricky. Yes, water ingress and corrosion could be a contributor as well as loss of pre-load or very high pre-load (axle nut too loose or too tight) and / or loss of lubrication. However, my ?guess? is the bearing cone & rollers are simply at the end of their fatigue lives. I don?t see corrosion elsewhere and I suspect you would have reported if the bearing was dry of grease.
I?d replace both lcone and the cup inside the wheel hub (both sides since the other side may be ready to give up), pack with Aeroshell 22 or Mobile 28 (be sure to squeeze grease into the roller cage ? yes, a bearing packer works great for this, but you can do it with your hands just as well), tighten the axle nut while slowly turning the wheel until you feel some resistance, then back off the nut about a ?flat or two?. There should be absolutely no wiggle of the wheel of any kind on the axle.
As far as inspections, you can use solvent to clear rollers / cones, MIL-PRF-680 Type II is the usual spec for solvents, but the key here is use low-pressure air to purge the solvent (don?t spin the bearing with air, however) then inspect and repack the bearings immediately. Replace any bearing that has any ding or deformation or loss of material - or one that has hit the floor. Stains can be OK if they are still smooth. The steel used in bearings is very susceptible to corrosion (even in mildly humid environments), so don?t let more than a few minutes go by from cleaning to inspection to re-packing. Or course, keep out the dirt / grime.
The prior comments about ball-bearings are interesting. Somebody might (and probably will) correct me on this, but I can?t think of a single ?modern- aircraft wheel application that uses ball bearings in place of roller bearings. Roller bearings do a great job resisting side loads inherent in aircraft wheel applications and tolerate the rapid spin-up upon touchdown, but maybe somebody has made a better mousetrap will a ball bearing setup.
Good Luck?