Is it permissible to keep an advanced part of a work device and hand over a less advanced part, while paying the price difference to the employer? And is this action considered something that angers God?

It is not permissible for an employee to take a part from their employer's computer and replace it with a less advanced one, even if they pay the financial difference, unless they have explicit permission from the employer. This is because the device is a trust (amanah (definition)) that must be returned as it is, and disposing of it without the owner's permission is not allowed.