First, isn't that D minor, C major, Bb (without third), A minor?
In addition to practicing slowly, a good way (in general) to practice is to practice hands separately until they can do their own thing well and only then start playing them together. Also try practicing just a single measure over and over again. When you can play every measure separately start practicing connecting them. This applies to both the hands separate and hands together phase.
Now there are lots of ways to finger these arpeggios. You could try to play some of the notes with the right hand but it might be a bit tricky with the melody (maybe even impossible, I didn't actually try it). Here are some ways to finger the arpeggios which suit my hand, each with their own strengths and weaknesses:
- 5-5(4)-2-1-2-5(4)-2-1 or similar for every arpeggio. That is, you play the first note with 5, then jump to a position where the chord fits comfortably in your hand and play the arpeggio. This will probably bring the base line out a bit, which may or may not be what you want. A strength here is that most of the arpeggio will be easy. A weakness is that the jump might not be easy, especially if you want the arpeggio to be very even.
- D minor, C major: 5-2-1-2-3-5-2-1, Bb: 5-2-1-1-3-5-3-1, A minor: 5-1-2-1-3-5-3-1. This is probably the most "fluid" version I could come up with, but it's also the least straightforward (so it might even require some practice just to get the fingers to play in the right order). It also has a jump in the Bb arpeggio with which you need to be careful with.
- All chords except A minor: 5-3-2-1-2-4(5)-1, A minor the same as in the previous one. This should work quite well if your hand is largish but might be problematic for smaller hands, though even then if you are able to play the required intervals you can practice a kind of wrist rotation technique to make it work.
Of course you can play one arpeggio with a fingering from (1) and another with one from (2) and so on, and you can modify these; I just tried to group them according to some common idea.