Maintenance is key here I think.
I ride mostly on land, but when i do go to the beach I strip, clean and repack my bearings every time. Takes about 30 mins to do, and can save not only a broken wheel/wheel bearing, but more importantly a broken bone due to a crash.
If you by bearings that have an RS in the number code, this stands for rubber seal. If you use a small watch repairers screwdriver (found in any pound shop), you can gently leaver out the seal, clean out the bearing (contact cleaner or white spirit works well), and then repack it with grease. For my beach wheels I use a specific white marine grease, land wheels just a general multi purpose grease.
I very rarely have to replace a bearing (only changed 2 in 3 years), and i do ride a great deal. Admitedly not as much as i would like on the beach, due to my location.
Also most important is adjusting the wheel bearing, to tight or to loose will cause premature wear/failure as previously mentioned. Thighten the nut until it just nips the bearing, and then back it off slightly. They do not need to have any pre load on them as they are not tapered bearings.