Parameterizing a Request in REST API Test using SoapUI Pro

The email address is the only unique field in this call, so two members cannot have the same email address.

I am trying to achieve 2 goals with this test:
1) Create any number of new members just by adding this SoapUI project to LoadUI, then let it run for as long as i want
2) Test the performance of the API itself under load

I thought there is a way to do this without the need of reading the data from an external datasource, by adding a code to the request body's itself.

Thanks.