Unique UUID value - PostgreSQL 9.2

I've got 2 tables:

Temp-Table
Table-A

Need to copy all the data from Temp-Table to Table-A. But there is a Constraint that does not allow me to have duplicated items.

So I need to create a Unique value.

Example:

Column Code        |   Column Info   | 
code_67493675936        info_2016

Question:

How can I do that using PostgreSQL 9.2?