Basically, wealth is the total value of assets.

No.  Wealth is the value of assets minus liabilities.  (Or is that what you meant by "total assets"?)  GDP is not wealth.  It is, roughly, the aggregate annual income of the nation being dicussed.  ("Roughly" because that doesn't take into account earnings from goods and services produced overseas.)  The US figure for GDP is somewhere in the neighbourhood of $13-14 trillion, I believe, but total wealth in the US is somewhere in the neighbourhood of $60 trillion.

Be nice to America. Or we'll bring democracy to your country.