it would be complicated/time consuming insuring modules individually; but it would have to be by 'each' module or you would have to adjust the botwise insurance amount each time a module was added or removed. And that would get irritating to have to accept or decline new insurance everytime you swap out a module.
The back end would have to scrape the market data on each module, as it does for the robots, to determine a dynamic replacement value.
The player could potentially be managing insurance on 100's (if not 1000's) of modules.
You could, in theory, limit insurance to T4 modules only to reduce that management.
The 'payout' would be, just like the bots, much less then the market costs. And the ultimate question is if managing insurance on modules would be worth the payback.
The 'final' hurdle, is simply that you can farm modules and repair them, you can't do that with bots. So, a possible 'scam' would be getting t4 drops off 5th stars, repairing them for less then the insurance payout, then putting them on light bots (or cheap mechs) and blowing them up for profit.