Imam Malik (may Allah have mercy on him) says that Umar (may Allah be pleased with him) expelled the people of Najran, but they were not expelled from the town of Tayma because it is not among the lands of the Arabs. As for al-Wadi (Wadi al-Qura), I think the Jews in it were not expelled because they did not regard it as part of the land of the Arabs.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجزية / 18758