I would say it's definitely not a bearing.
The piston. in the caliper will be corroded, if you can obtain new seals than remove the pistons and carefully clean the rust off them with wet & dry and rebuild. It doesn't always work as it depends on how bad they are corroded.
Easier option is to fit new calipers
cost is somewhere in the region of £65 to £80 to £149 each depending on type
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