To get to Matera from Sorrento you should change bus in Naples.
From Naples there are two daily bus rides connecting Naples to Matera:
The buses, of the company Soc. Marino s.r .l, leave from Napoli Porta Garibaldi, front of hotel Cavour at 2 and 5 pm. The ride takes about 4 hours and will take you to Matera , via Don L.Sturzo, Chiesa San Paolo.
The ticket costs 20.00€ each ride or 36.00€ return ticket.