Insurance companies have some very distinct metrics of evaluation such as solvency ratio and embedded value (EmV).
Solvency ratio of an insurance company is the ratio of its net assets to the risks it has taken, usually net written premiums whereas Embedded Value (EmV) is the sum of adjusted net worth and the present value of the future profits.
The ratio of the company's market cap and the embedded value i.e the Price to Embedded Value Ratio (P/EmV) can be used to compare the valuation of life insurance companies.
One can also use Price to Book Value Ratio (P/BV) which compares a firm's market capitalization to its book value. A high P/BV indicates markets believe the company's assets to be undervalued and vice versa.