Praise be to Allah.
You are correct in describing what you friend said about the Qur’aan being contradictory as a misconception or misinterpretation. It is either because your friend has misunderstood something or he is being stubborn and is looking for a specious argument to stir up doubts in the hearts of some Muslims who are ignorant about their religion. Hence the advice we offer to all our Muslim brothers is not to indulge in debate with the followers of falsehood before arming themselves with knowledge with which they can ward off these specious arguments. They should leave this to those who are qualified for it, namely the scholars who are well versed in knowledge and the seekers of knowledge who have a solid base of knowledge, because a specious argument may enter one’s heart and have a serious effect, and it is better to err on the side of caution.
With regard to this particular issue, there is no contradiction between the two verses, praise be to Allaah. It was answered by the scholars of tafseer in the past; al-Raazi said in his Tafseer, when commenting on the verse in Aal ‘Imraan: What is meant by the angels here is Jibreel alone. It is like the verse in which Allaah says (interpretation of the meaning): “He sends down the angels with the Rooh (Revelation) of His Command to whom of His slaves He wills” [al-Nahl 16:2], meaning Jibreel. End quote.
This is nothing strange in Arabic, where the plural may be used to refer to the singular. There are many such examples in the Qur’aan, such as the verse in which Allaah says (interpretation of the meaning): “Those (i.e. believers) unto whom the people (hypocrites) said, “Verily, the people (pagans) have gathered against you (a great army), therefore, fear them.” But it (only) increased them in Faith, and they said: “Allaah (Alone) is Sufficient for us, and He is the Best Disposer of affairs (for us)” [Aal ‘Imraan 3:173].
What is meant by al-naas (the people) in the first case is Na’eem ibn Mas’ood, and in the second case is Abu Sufyaan and his companions. It does not mean all the people.
Imam Ibn ‘Atiyyah said in his tafseer al-Muharrar al-Wajeez: The word al-malaa’ikah (the angels) is used to refer to Jibreel because he is one of them, so the name of the race is used, as in the verse (interpretation of the meaning): “Those (i.e. believers) unto whom the people (hypocrites) said,” [Aal ‘Imraan 3:173]. End quote.
And Allaah knows best.